1. Field of the Invention
This invention relates to a device for mounting on a vehicle wheel in girdling relation to a tire to enhance traction of the tire with an underlying surface on occasions when the condition of the surface degrades traction between itself and the tire tread. The device is intended for use during winter driving conditions when a vehicle may at times have to travel on ice and/or snow.
2. Background Information
For many reasons, tire packaging is a significant consideration in the design of a motor vehicle. Suspension and steering systems define geometric envelopes for relative positions of wheels and tires with respect to a vehicle body and chassis. The design of a particular vehicle model may call for an ability to accept a range of size tires. Tire packaging also bears on vehicle appearance and handling characteristics.
The design of mass-produced motor vehicles typically calls for tire packaging that permits the mounting of traction assist devices, such as tire chains, on the wheels, even if such devices will actually be used on only a relatively small percentage of all such vehicles. Because such devices girdle the profile of a wheel-mounted tire in covering relation to both tire tread and tire side walls, sufficient dimensional clearances must be designed into the geometry of a mass-produced vehicle beyond those required to accommodate the various design considerations mentioned above. Accordingly, it would be desirable if the extra dimensional clearances that have to be designed into a motor vehicle to accommodate such traction assist devices could be minimized. However the ability to minimize those clearances is largely dependent on minimizing the size of the traction assist device itself.
Besides the fairly popular metal tire chains, there are other traction assist devices that are already known, although perhaps not as extensively used. They include tire cables, single-sided chains, and studded shells, and some may allow a vehicle manufacturer to reduce dimensional clearances between tire envelopes and the body and chassis of a motor vehicle when compared to clearances required for metal tire chains.
A preliminary novelty search developed the following U.S. Pat. Nos. 1,718,509; 1,932,576; 4,280,544; 4,346,748; 4,718,949; and 4,919,182. As suggested by this state of the art, traction assist devices can be fabricated from synthetic materials (i.e. plastics). Those devices can wrap fairly snugly around a tire to girdle the tread, and as the wheel revolves, they are not prone to slinging rungs of a tire chain outwardly as known metal tire chains are apt to do.
Various means are employed to secure the known traction assist devices in place on a wheel and tire. For certain devices a number of separate parts are required, and tools may also have to be used to join parts fast to one another. It is believed that improvements in securing a traction assist device in place on a wheel and tire, especially a device fabricated from synthetic material to have a low-profile, would be a useful advance in traction assist technology that could aid not only in minimizing clearance requirements but also in facilitating installation of the device on a vehicle wheel.
The invention relates to a traction assist device which can be mounted on a motor vehicle tire to girdle the tire in a low-profile relation to the tire tread, which can be conveniently and quickly mounted without having to assemble individual parts and fasten them together, which can be installed manually without the use of tools, which allows slack in the fit to a tire to be taken out so that the device can be more tightly secured on the tire, which can be economically fabricated, and which enables a vehicle to be designed with smaller clearances between tire envelopes and a vehicle body and chassis.
A general aspect of the invention relates to a traction assist device for girdling a motor vehicle tire comprising a pair of side bars for fitting against opposite side walls of the tire and a number of transverse bars extending between the side bars at intervals along the length of the side bars. Each transverse bar extends from one of the side bars and across a tread of the tire to the other side bar when the device is mounted on the tire. Each side bar comprises respective ends that cooperatively form a connector for connecting the respective ends together when the device is mounted on the tire. One end of each side bar comprises a male connector portion of the respective connector and the opposite end of each side bar comprises a female connector portion of the respective connector within which the corresponding male connector portion is received when the respective connector portions are connected together. Each male connector portion comprises a serrated zone containing serrations. A respective pawl is associated with each female connector portion and comprises a serrated zone containing serrations for engaging at least one serration of the serrated zone of the respective male connector portion with at least one serration of the serrated zone of the respective female connector portion when the device is mounted on the tire.
Another general aspect of the invention relates to a traction assist device adapted for girdling a motor vehicle tire and comprising a nominally flat polymeric part that can assume a circular shape for fitting onto a tire. The polymeric part comprises a pair of side bars that are nominally straight, but can assume circular shapes for fitting against opposite side walls of the tire. The polymeric part further comprises a number of transverse bars integrally joining with the side bars and extending between the side bars at intervals along the length of the side bars. Each transverse bar is nominally straight, but when the device is mounted on the tire, each transverse bar fits closely against the tire, extending from one of the side bars, thence wrapping over and across a tread of the tire to the other side bar. Each side bar further comprises respective ends that cooperatively form a respective connector for connecting the respective ends together when the device is mounted on the tire.
Further aspects will be seen in various features of a presently preferred embodiment of the invention that will be described in detail and in principles of the invention as set forth in various claims.